It is well known that insects can cause significant damage, not only to crops grown in agriculture, such as wheat, corn, soybeans, potatoes, and cotton but also, for example, to structures and turf where the damage is caused by soil-borne insects, such as termites and white grubs. Such damage may result in the loss of millions of dollars of value associated with a given crop, turf or structure. Insecticides and acaricides are useful for controlling such insects and acarids.
A number of patents and publications disclose a variety of dihalopropene compounds that are reported to be insecticidally and acaricidally active. For example, U.S. Pat. No. 5,922,880 discloses certain dihalopropene compounds containing optionally substituted heterocyclic ring groups for use as insecticides and acaricides. Examples of the heterocyclic ring in the optionally substituted heterocyclic ring group are isoxazole, thiazole, 1,3,4-thiadiazole, pyrrole, furan, thiophene, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, 1,2,3,4-tetrazole, pyridine, pyridazine, pyrimidine, pyrazine, 1,2,4-triazine, 1,3,5-triazine, indole, benzofuran, thianaphthalene, indazole, benzimidazole, benzotriazole, benzisoxazole, benzoxazole, benzothiazole, quinoline, isoquinoline, quinoxaline, quinazole, piperidine, piperazine, tetrahydrofuran, tetrahydropyran, pyrazoline, phthalimnide, dioxane, dioxolane, and benzodioxolane (Column 3, lines 15-25).
Insecticides containing dihydrobenzofuranyl substituents are also known in the art. See, in this regard, U.S. Pat. Nos. 3,474,170 and 3,474,171 which disclose dihydrobenzofuranyl esters of carbamic acids.
In addition to activity against target pests a commercially viable pesticide needs to satisfy a number of additional criteria including, inter alia, production costs, environmental impact, mammalian toxicity, lack of undesirable effects on target crops and certain physical characteristics. Desirable physical characteristics for a compound to be used in an outdoor field environment include inter alia, photochemical stability under field conditions. Photostable insecticides and acaricides, i.e., those which do not break down or degrade when exposed to sunlight, are advantageous in that they provide long-term insecticidal and acaricidal activity, which increases the effectiveness of the active compound.
Efficacy problems associated with pesticides that have limited photostability are well known. For example, Clough et al. (Fungicidal β-Methoxyacrylates; Synthesis and Chemistry of Agrochemicals, ACS Symposium Series 504, Chapter 34 (1992)) describes disappointing fungicidal activity of certain compounds when tested in light, and efforts to synthesize fungicides with greater photostability. In another example, Shiokawa, et al. (Chloronicotinyl Insecticides: Development of Imidacloprid; Eighth International Congress of Pesticide Chemistry-Options 2000, ACS Publication 1995) describes the wavelengths of sunlight that reach the earth's surface that can cause photo-degradation of certain compounds such as nitromethylene insecticides and other compounds.
Accordingly, there is a continuing demand for new insecticides and acaricides that are safe, more effective e,g, more photostable, and less costly to prepare on a commercial scale.